After undergoing chemotherapy, most breast cancer patients, 57.1% (20/35), 62.9% (22/35), and 60% (21/35) patients showed increased PD-1, PD-L1, and PD-L2 expression, respectively (mean fold change: 6.65, 2.93, and 5.88 for increased PD-1, PD-L1, and PD-L2). Here, PDCD1LG2 is linked to breast cancer.